1. Field of the Invention
The present invention relates to electrical connectors and, more particularly, to electrical connectors mounted to Printed Circuit Boards by boardlocks.
2. Description of the Related Art
Surface Mounting Technology (SMT), as applied to Printed Circuit Board (PCB), is the recent trend for the Assembly Industry. SMT is a technique used for mounting connectors and their corresponding connector pin solder tails (e.g., J or Gull-wing leads) directly to one surface of a PCB. When employing this technology, the PCB requires solder paste printing at the contact regions which the corresponding pin tails of an electrical connector are to seat against. The region to be soldered is exposed to a reflow process such as vapor phase, or convection or radiant infrared (IR) which electrically couples the pin tail to the contact region without the occurrence of solder shorts. This technique is advantageous, not only because SMT offers a high degree of soldering precision when applied to selected areas, but also because the electronic components and connectors may be mounted to both sides of the PCB (dual-sided PCB).
In contrast, the conventional method of coupling connector pin tails to a PCB is by inserting the connector pin tails through an array of apertures provided in the PCB and soldering the pin tails to the opposing surface of the PCB using a process known as wave-soldering. This latter method is conventionally known as "through-hole mounting," which, generally, offers a much better retention capability for the pin tails than SMT can provide.
One problem, however, is that wave-soldering usually may not be employed to a dual-sided PCB which includes surface mounted ICs, or passive and discrete components. The wave-soldering technique could permanently damage these components. Moreover, "through-hole mounting" is space inefficient because this technique occupies space on both surfaces of the PCB. Accordingly, SMT often is preferable.
An additional problem associated with wave-soldering is that the holes in the second side of the PCB for holding the second side components are filled with solder when the components on the first side of the PCB are soldered. The solder in the second side PCB holes prevents insertion of the second side component legs into the holes.
In many instances, when the pin tails are all housed in one electrical connector, it is desirable to secure the electrical connector itself to the PCB employing SMT.
Often, the adhesion of the connector pin tails to the PCB surface is sufficient to retain connector or component to the surface without additional supplements. This can be most beneficial because, generally, this eliminates the need to attach the connector to the PCB using a separate process.
However, electrical connectors can be exposed to significant mechanical stress. Securing only the pin tails of the connector to the PCB often does not always adequately secure the connector to the PCB. For example, an Input/Output (I/O) connector typically endures a greater number of connector insertions or withdrawals of the corresponding mating connectors. In particular, an I/O electrical connector, such as a D-Subminiature Connector (named for its "D" shape in cross-section), can require additional mounting fixtures. In these instances, it may be desirable to employ a "through-hole mounting" fixture, which typically precludes usage of dual-sided PCBs.
For example, "boardlocks" are one kind of additional mounting support which provide a means for removably mounting the electrical connector to a first PCB surface. Unfortunately, under current practices, SMT generally cannot be applied to boardlocks because the amount of solder predisposed on the PCB surface during the solder paste printing manufacture stage is insufficient to properly retain the boardlock to the opposing second PCB surface. Substantially more solder generally is required to retain the "boardlock" than to retain the contact tail pins.
Therefore, "boardlocks" are typically mounted to the PCB surface using soldering processes other than SMT such as a wave-soldering process. However, as previously mentioned, a wave-soldering process can preclude certain combinations of dual-sided PCB component mountings, such as surface mounted ICs, or passive and discrete components, for example.
Another problem often encountered when applying SMT is that the solder pin tails sometimes can be slightly misaligned from the corresponding printed circuit. Proper placement is, of course, essential to the functioning of the electrical connector. Thus, it is desirable that the tails be properly aligned with the PCB to assure proper contact with the corresponding printed circuit.
Accordingly, there has been a need for an electrical connector which can be more securely mounted to a PCB using SMT. There has also been a need to provide an electrical connector which more precisely aligns the conductive tails against the surface mounted circuits of the PCB. The present invention meets these needs.